1. Field of the Invention
The invention relates to a holder for membrane filters, such as is used to remove particulate matter from intravenous solutions entering the circulatory system of a human. The invention also relates to a method of assembling a membrane folding holder from a fusible enclosure by application of induction heating to heat the metal disk and seal the fusible enclosure to the disk and to the membrane.
2. Description of the Prior Art
Filters manufactured from high strength synthetic polymer materials can be formed by a process designed to achieve a structure consisting of an ultrathin skin containing micro screening pores supported by an extremely pervious substructure. Such filters having an ultrathin screening surface and highly porous support give extraordinarily high flow rates observed at very low pressures. The extremely small surface pore size insures the complete elimination of particulate matter, including bacteria and viruses, and the ultrafilters are particularly resistant to plugging and fouling by many industrial and medical fluids. Such filters have particular utility in removing particulate matter from intravenous solutions administered to a human, since such particulate matter can lead to serious deleterious medical effects. Holders developed for such filters, however, have had shortcomings and drawbacks.
Particularly for the medical applications outlined above, filter holders in an intravenous feed line have been developed, such as the device shown in U.S. Pat. No. 3,471,019, issued Oct. 7, 1969, to Trasen, et al., showing a filter unit sealed together by pressing two parts of a housing surrounding filter, and fusing the sealing portions of the housing parts by ultrasonic welding. Many materials for construction of the filter holder have poor characteristics for ultrasonic sealing, or have poor characteristics for solvent welding. Furthermore, the filter unit of the Trasen et al patent requires a plurality of upstanding rib means to support the filter in order to enable it to withstand the pressure of fluid flowing therethrough without tearing.
Other patents showing filtering devices include U.S. Pat. Nos. 3,854,907 and 3,149,758.